[1] Born in Dayton, Columbia County, Washington,[2] He became an actor in his twenties, with a first known film credit listed in the 1915 short The Fool's Heart.

[4] Engaged by Universal Pictures' early silent film subsidiary, Bluebird Photoplays, as leading man to Ruth Clifford in 1918's The Lure of Luxury, Hearn was subsequently put under contract with the low-budget studio Film Booking Offices of America (also known as FBO Pictures Corporation)[5] and alternated between roles as leading man (to Ruth Renick in Tahiti-filmed The Fire Bride (1922), Jane Novak in Colleen of the Pines (1922), Gladys Walton The Town Scandal (1923), Laura La Plante Excitement (1924), and Josie Sedgwick in The Outlaw's Daughter (1925), and second leads, billed after Patsy Ruth Miller, Ralph Graves and Edna Murphy in Daughters of Today (1924).

[citation needed] In 1925, Hearn was fourth-billed as Clara Bow's brother in The Lawful Cheater, a crime drama fashioned as a vehicle for the flapper star, while he also had a rare first-billed role as the central character, Philip Nolan, in Fox Film Corporation's adaptation of Edward Everett Hale's classic short story, "The Man Without a Country".

He was also top-billed in a minor 1924 western, The Devil's Partner, which not released until 1926, the year he was the human leading actor in a May vehicle for the dog star Peter the Great, a German Shepherd who, after appearing in one more film, was fatally shot in June.

[citation needed] In 1926, he was Helen Holmes' leading man in Perils of the Rail, while playing an unbilled cameo as a Union Army officer in another railroad-centered film, Buster Keaton's The General.

[citation needed] In 1928, as Hearn reached his fortieth birthday, his changing fortunes were reflected through the six productions in which he appeared.

In 1930 Hearn had small supporting roles in three features and an unbilled part in a Charley Chase - Thelma Todd Hal Roach two-reeler, but it was 1931 that set the pattern for the remainder of his career.